When a battery-operated power tool is transported to a work site, a storage case may be used to conveniently transport the power tool and auxiliary related devices, such as a charger and a battery pack(s). However, even when a user carries the storage case to the work site, the user generally discharges power from the battery pack faster than the battery pack is able to be charged, and the availability of charging power sources (e.g., AC outlet, DC cigarette lighter outlet, etc.) is often unavailable or limited and/or does not provide enough power and energy to keep up with demand.